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2017-02-27 本文已影响0人
三花Dixon
Assignment 1
秦堤
2014013420
2.4 Yes, because we can identify tuples uniquely by the attribute name.
2.7 a. \(\Pi_{person\name}(\sigma{city=Miami}(employee))\)
b. \(\Pi_{person\name}(\sigma{salary>$100,000}(works))\)
c. \(\Pi_{person\name}(\sigma{salary>$100,000}(works))\cap\Pi_{person\name}(\sigma{city=Miami}(employee))\)
